Knee-stretching Device and Treatment Methods

ABSTRACT

A knee-stretching device and methods of increasing knee range of motion in extension are disclosed. The knee-stretching device allows a patient to self-stretch and acts as a first class lever, applying force supplied by the patient&#39;s arms to the knee through the distal portion of the leg. The knee-stretching device can apply traction, varus, and valgus forces in addition knee extension force. Disclosed treatment methods include the use of the knee-stretching device before surgical intervention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 60/758,182, filed on Jan. 10, 2006, the contents of which are incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to the fields of rehabilitation and physical therapy and, more specifically, to rehabilitation devices and methods for the knee.

2. Description of Related Art

The knee joint is one of the more complex and important joints in the human musculoskeletal system. Together, the knees essentially support the entire body weight during most types of upright movement. In particular, knee strength, stability, and range of motion are very important for proper standing, walking, and running.

There are a number of ways in which the normal function of the knee joint may be impaired. For example, one or both of the anterior and posterior cruciate ligaments that stabilize the knee may be torn or damaged. Tears in the menisci between the femur and the tibia may cause those bones to grind together. Years of use may result in wear on the menisci, the articular cartilages, and the bones themselves, sometimes requiring a knee replacement (i.e., a total knee arthroplasty). Any of these problems may cause a loss of knee stability and/or range of motion, resulting in an inability to stand or move properly. Other orthopedic and neurological conditions may also cause loss of knee range of motion, abnormal knee wear, and loss of knee stability.

An important part of the standard of care for knee injury, and for other conditions affecting the knees, is physical therapy aimed at increasing knee strength, range of motion, and function. In conditions that warrant corrective surgery, physical therapy is commonly prescribed in addition to surgery in order to restore knee strength, range of motion, and function after surgery.

During a physical therapy regimen, a physical therapist may stretch a patient's knee manually. However, it is also advantageous if a patient can stretch him- or herself. Self-stretching may help to avoid the pitfalls of overstretching the joint and allows the patient to continue therapeutic stretching exercises outside of the clinical setting and without assistance from a therapist. Stretching at home can result in faster recovery, improved outcomes, and decreased cost.

SUMMARY OF THE INVENTION

One aspect of the invention relates to a knee-stretching device. The knee-stretching device comprises a lever portion, a fulcrum portion, a harness, and an out-of-plane pivot. The lever portion is elongate and has first end and a second end. The fulcrum portion is pivotally connected to the lever portion intermediate the first and second ends. The fulcrum portion has an upper end and a lower end. The upper end of the fulcrum portion is connected to the lever portion through a lever pivot. The lower end of the fulcrum portion is adapted to rest on a leg. The harness is connected to the lever portion proximate to the second end. The out-of-plane pivot connects portions of the knee-stretching device and allows at least a part of the lever portion to transmit force in a plane other than a knee flexion-extension plane of motion, such that the knee-stretching device is adapted to transmit forces to the distal portion of the leg in the knee flexion-extension plane of motion and in other planes of motion.

Another aspect of the invention relates to a method of increasing knee strength, function, or range of motion in a patient. The method comprises causing the patient to simultaneously apply a knee extension force and one or more forces selected from the group consisting of a traction force on the knee, a varus force on the knee, and a valgus force on the knee using a first class lever device positioned to accept force from the arms of the patient and transmit that force to the patient's knee through the distal portion of the patient's leg.

Yet another aspect of the invention relates to a knee-stretching device. The device comprises lever means, harness means, fulcrum means, and out-of-plane pivot means. The lever means accepts a manual force and applies that force to a knee through a distal portion of a lower extremity. The harness means is coupled to the lever means and holds the distal portion of the lower extremity. The fulcrum means is pivotally connected to the lever means and allows the lever means to pivot in a first plane of motion while the fulcrum means remains fixed in position. The out-of-plane pivot means allows the lever means to transmit force in the first plane of motion and in planes of motion other than the first plane of motion.

These and other aspects, features, and advantages of the invention will be explained in the description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with respect to the following drawing figures, in which like elements are indicated by like reference numerals throughout the drawings, and in which:

FIG. 1 is a perspective view of a knee-stretching device according to one embodiment of the invention;

FIG. 2 is a side elevational view of the knee-stretching device of FIG. 1 in use;

FIG. 3 is a side elevational view of the knee-stretching device of FIG. 1, illustrating the length adjustment of the lever portion;

FIG. 4 is a sectional view of a portion of the knee-stretching device of FIG. 1 taken through Line 4-4 of FIG. 1, illustrating the attachment of the lever portion and the fulcrum portion;

FIG. 5 is a top plan view of the knee-stretching device of FIG. 1 in use, illustrating the device applying knee extension, traction and valgus force to a patient's knee;

FIG. 6 is a top plan view of the knee-stretching device of FIG. 1 in use, illustrating the device applying knee extension, traction and varus force to a patient's knee;

FIG. 7 is an elevational view of the knee-stretching device taken through Line 7-7 of FIG. 1, illustrating the rotational range of motion of its second end which is used in applying a varus or valgus force to the knee;

FIG. 8 is a side elevational view of a knee-stretching device according to another embodiment of the invention; and

FIG. 9 is a top plan view of the knee-stretching device of FIG. 8.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of a knee-stretching device, generally indicated at 10, according to one embodiment of the invention. FIG. 2 is a side elevational view of the knee-stretching device 10 in use. The knee-stretching device 10 includes a lever portion 12 and a fulcrum portion 14 arranged such that the knee-stretching device 10 acts as a first class lever. As will be described below in more detail, the knee-stretching device 10 allows a patient to stretch his or her own knee.

The lever portion 10 includes a first end 16 and a second end 18. In the illustrated embodiment, the lever portion 10 is made of a substantially rigid, tubular material, such as aluminum or steel. The first end 16 is capped by a grip 20, which may be plastic or rubber, such that the first end 16 is adapted to be grasped by a user. The second end 18 is also provided with a cap 22, which may also be formed of plastic or rubber.

The fulcrum portion 14 is located intermediate the first and second ends 16, 18, and has an upper end 24 and a lower end 26. The upper end 24 of the fulcrum portion 14 defines a pivot 28, which, in the illustrated embodiment, comprises a bolt 29 that passes through the lever portion 12 and is supported on each end by a support 30, one on each side of the fulcrum portion 14. (The bolt 29 itself is best seen in the view of FIG. 4 and is shown as being threaded along substantially its entire length, although this need not be the case in all embodiments.) Each support 30 comprises a plate or tongue of material with an opening sized and adapted for the bolt 29. As mounted to the fulcrum portion 14 through the pivot 28, the lever portion 12 is free to rotate in a plane, as illustrated by the arrows in FIG. 2, such that a movement in one direction of the first end 16 of the lever portion causes a movement in the opposite direction of the second end 18. For example, if a user pulls down on the first end 16, the second end 18 is caused to rise. As a whole, the lever portion 12 can rotate clockwise or counterclockwise in its plane of motion.

The midsection 32 of the fulcrum portion 14 in the illustrated embodiment is comprised of a section of square tubing, the upper ends of which have been modified to form the supports 30 for the pivot 28. The lower end 26 of the fulcrum portion 14 is attached to the midsection 32 and comprises a generally rigid, semi-cylindrical thigh rest 34 that, as shown in FIG. 2, is adapted to rest on the leg of a user. Adhered to the inner, concave surface of the thigh rest 34 is a layer of foam padding 36. The padding 36 is intended to make the thigh rest 34 rest more comfortably on the leg.

Near to the second end 18 of the lever portion 12, a harness 38 is mounted to the lever portion 12 by looping it through an eyebolt 40 that is secured to the lever portion 12. The harness 38 of the illustrated embodiment is a simple strap made of nylon, canvas, or some other sturdy, flexible material, and includes a buckle 42 that can be used to adjust the length of the harness 38 and allows the harness 38 to be disengaged in order to remove the harness 38 from the eyebolt.

The harness 38 is adapted to support and apply force to the distal portion of the leg near to the ankle. In other embodiments, the harness 38 could have any features that facilitate that function, including padded areas to increase user comfort, multiple straps to increase hold, or areas of hook-and-loop fastener for easy release. In general, harnesses are well known in the art of rehabilitative devices, and any features conventionally applied to a harness may be applied to the harness 38. Moreover, although the harness 38 of the illustrated embodiment is a flexible harness, other embodiments of the invention may include rigid or semirigid harnesses pivotally attached to the second end 18 of the lever portion. For example, a harness could be made of metal tubing and connected to the second end 18 so that it can be rotated into appropriate angular positions.

As shown in FIGS. 1 and 2, the first and second ends 16, 18 of the lever portion 12 are upturned with respect to the central section of the lever portion 12. That is, the section of the lever portion 12 near to the first end 16 makes an acute angle with the horizontal, as does the section of the lever portion 12 near to the second end 18. This feature provides the lever portion 12 with more vertical clearance when the knee-stretching device 10 is in the operational position shown in FIG. 2, with the thigh rest 34 of the fulcrum portion 14 positioned on the leg just proximal to the knee joint and the harness around the distal portion of the leg. Additionally, as shown in the figures, the eyebolt 40 is positioned so that the harness 38 attaches on an upper surface of the lever portion 12, rather than a lower surface, which uses the vertical clearance space more effectively and also provides certain other advantages that will be described in more detail below.

As was noted briefly above, the lever portion 12 and the midsection 32 of the fulcrum portion 14 in the illustrated embodiment are comprised of hollow, tubular rigid materials that are welded, affixed with fasteners, or otherwise secured together as appropriate. The precise method of securement of the attached parts of the knee-stretching device 10 is not critical. Moreover, in other embodiments of the invention, the knee-stretching device 10 may be constructed of solid, rather than hollow tubular, materials.

However, forming the lever portion 12 out of tubular materials has a particular advantage: the lever portion 12 can be divided into two or more segments that nest within each other so that the length of the knee-stretching device 10 can be adjusted and the device 10 can be collapsed for storage or shipping.

FIG. 3 is a side elevational view of the knee-stretching device 10, illustrating the adjustment of the length of the lever portion 12. More particularly, FIG. 3 illustrates a first length “A” of the lever portion 12 and a second length “B” of the lever portion 12 in phantom lines. Depending on the embodiment, the length adjustment mechanism may allow the selection of an arbitrary length over the entire range of possible lengths offered by the lever portion 12, or it may allow the selection of one distinct plurality of specific lengths.

The length adjustment mechanism illustrated in FIGS. 1-3 is a continuous length adjustment mechanism that allows the selection of an arbitrary length. FIG. 4 is a sectional view taken along Line 4-4 of FIG. 1, illustrating the pivot 28 and the length adjustment mechanism in more detail.

As shown in FIG. 4, the lever portion 12 comprises an outer tubular first part 44, inside of which is fixed an adapter part 46. A moveable part 48 of the lever portion 12 is slidably mounted on the adapter part 46 beyond the pivot 28. The moveable part 48 has a diameter that allows it to slide easily along the adapter part 46, and for reasons that will be explained in more detail below, the moveable part 48 is also permitted to rotate or pivot about the adapter part 46. Fixed to the exterior of the moveable part 48 is a clamping split ring 50 with a diameter that is adjustable by adjusting a fastener 52 (shown in FIGS. 2 and 3) that joins the ends of the split ring 50. The fastener 52 may be, for example, an Allen head machine screw or a hand screw.

To adjust the length of the lever portion 12, the user would loosen the fastener 52 in the split ring 50, slide the moveable part 48 to the desired length, and re-tighten the split ring 50. During the adjustment, the user may also rotate the moveable part 48 with respect to the first part 44 and the adapter part 46. Thus, the first and adapter parts 44, 46 provide an out-of-plane pivot that allows the moveable part 48 to move out of the knee flexion-extension plane of motion and apply force in planes other than the knee flexion-extension plane of motion. The adapter part 46 and moveable part 48 may be painted or inscribed with length markings and rotational markings, if desired, in order to provide the user with length and rotational references as he or she is adjusting the length of the lever portion 12 and the rotational position of the moveable part 48.

In other embodiments, the clamping mechanism that is used to adjust and fix the length of the lever portion 12 may be implemented in other ways. For example, the clamping function may be performed by an over center clamping bolt and split ring assembly of the type commonly used to clamp a seatpost of a bicycle to the bicycle frame. The clamping function could also be performed by a threaded clamping device of the sort commonly used on adjustable tripods.

The bolt 29 that defines the pivot 28 passes through both the first and adapter parts 44, 46 to secure the two of them together. On at least one side, a spacer 54, such as a washer, is provided to ensure that the lever portion 12 will be free to rotate. In addition to the securement shown in FIG. 4, the first part 44 and the adapter part 46 may also be secured together, for example, by welding, gluing, or by giving the adapter part 46 an interference fit within the first part 44.

The knee-stretching device 10 may thus be used to stretch the knee joint. As shown in FIG. 2, the user applies a downward force on the first end 16 of the lever portion 12 and a proportional stretching force in the opposite direction is created at the second end 18 of the lever portion. The stretching force acts on the knee joint through the distal portion of the leg and causes the knee joint to extend.

In addition to knee extension, the knee-stretching device 10 is also adapted to apply traction and/or varus or valgus forces to the knee joint. Stated otherwise, the knee-stretching device 10 can combine knee extension force with traction and/or varus or valgus forces. In this description, the term “traction” should be construed to refer to a force, generally applied in a proximal-to-distal direction, that draws the bones of a joint—in this case, the knee joint—apart. The term “varus force” should be construed to refer to a force applied proximal and distal to the knee in a direction toward the midline of the body, while the term “valgus force” should be construed to refer to a force applied proximal and distal to the knee in a direction away from the midline of the body.

With respect to traction, as shown in FIG. 2, the harness 38 is not positioned such that it hangs straight down; rather, it hangs down and supports the distal portion of the leg at a particular angle. The angle at which the harness 38 is positioned allows it to apply a traction force to the knee joint, the extent of which is determined in part by the amount of force applied by the user to the first end 16 of the lever portion 12 and in part by the angle at which the harness 38 is positioned, among other factors.

The application of valgus and varus forces is illustrated in FIGS. 5 and 6, which are top plan views of the knee-stretching device 10 in use, applying valgus and varus forces, respectively. As was noted above, the moveable part 48 of the lever portion 12 can be rotated with respect to the adapter part 46. When the moveable part 48 is pivoted away from the midline of the body, the lever portion 12 can apply a valgus force to the knee joint. When the moveable part 48 is pivoted toward the midline of the body, the lever portion 12 can apply a varus force.

FIG. 7 is an elevational view of the knee stretching device 10 taken through Line 7-7 of FIG. 1, illustrating the rotational range of motion of the moveable part 48 of the lever portion 12. For clarity, the first end 16 of the knee-stretching device 10 has been cut away. As shown, the user may select any angle of rotation of the moveable part 48, which includes the second end 18 and the eyebolt 40 to which the harness 38 attaches, in order to create varus or valgus forces when the knee-stretching device 10 is in use. In the illustrated embodiment, the lever portion 12 does not include movement stops to restrict the rotational range of motion of the moveable part 48; however, appropriate movement stops could be incorporated into the lever portion 12 in other embodiments of the invention.

When the moveable part 48 is rotated, the position of the eyebolt 40 determines, at least in part, the orientation of the harness 38 and, thus, the forces that are applied. Additionally, the position of the eyebolt 40 on an upper surface of the lever portion 12 reduces the amount of slack and tends to increase the ability of the harness 38 to be positioned at particular angles with less rotation of the moveable part 48 of the lever portion 12. However, in other embodiments, the eyebolt 40 may be attached to a lower surface of the lever portion 12.

In use, the knee-stretching device 10 can apply traction and/or varus or valgus forces with knee extension force. The forces that are applied in any particular case depend on the angular position of the moveable part 48 of the lever 12, as shown in FIG. 7, and the angle of the harness 38 with respect to the patient's tibia, as shown in FIG. 2. The angle of the harness 38 with respect to the patient's tibia may be adjusted by adjusting the length of the lever portion 12. The particular types of forces that are applied in any particular case may be determined by the user (i.e., the patient) or by the clinician or clinicians who are prescribing the knee stretching.

As those skilled in the art will appreciate, the knee joint itself has medial and lateral aspects where the medial and lateral condyles of the femur and tibia meet and are cushioned by respective medial and lateral menisci and articular cartilage. In some knee injuries, one of the medial or lateral aspects of the knee joint is more damaged, sensitive, or worn than the other. By applying an appropriate varus or valgus force, a user can selectively unload the more worn or damaged condyle of the joint so as to achieve better knee extension with less discomfort. Traction forces applied to the knee joint would tend to distract both the medial and lateral aspects of the knee joint and prevent them from grinding together during knee extension. Thus, the knee stretching exercise can be tailored to the needs of each patient so as to provide beneficial stretching with maximum therapeutic effect and, hopefully, less discomfort.

The particular dimensions of the knee-stretching device 10 may vary from embodiment to embodiment, depending on the size of the patient in question and the amount of force that is to be applied. In one advantageous configuration, the knee-stretching device has an overall, fully extended length of approximately 5 feet, with the fulcrum portion 14 located approximately 3 feet from the first end 16 of the lever portion 12, as measured along the length of the lever portion 12. The first and second ends 16, 18 are upturned such that they make an angle of about 15 degrees with the horizontal, the bends being positioned at approximately 1.6 feet and approximately 4.2 feet from the first end 16, as measured along the length of the lever portion 12. With dimensions on this order and the ability to adjust to longer and shorter lengths, the knee-stretching device 10 can accommodate approximately 80-90% of the U.S. adult populace (heights from about 5 foot, 2 inch to about 6 foot, 2 inch). Longer and shorter versions of the knee-stretching device 10 may be made.

Various modifications may be made to the knee-stretching device 10 in order to make it easier to use and in order to enable use with other treatment methodologies. For example, the first end 16 of the lever portion 12 could be fitted with a post or stop. Weights could then be placed around the post or around the circumference of the first end 16 abutting the stop, so that the patient is not required to apply as much force when using the knee-stretching device 10. The position of the fulcrum portion 14 along the lever portion 12 could be made adjustable, so that, for example, patients with less arm strength would have more leverage. The foam padding 36 could be modified to allow the placement of an electrical stimulator, which would allow the patient to stretch while also stimulating the quadriceps muscles to contract. Heating pads or ice packs may also be strapped to the back of the knee during use of the knee-stretching device 10.

Some of the modifications to the knee-stretching device 10 may impart measurement capabilities. For example, a force gauge could be incorporated into the second end 18 or the fulcrum portion 14 to allow the patient to measure how much force is being applied. An integrated force gauge and timer could also be incorporated, and would allow a therapist to determine exactly how much and how well the patient is using the device. A goniometer may also be built into the knee-stretching device 10 to measure the knee angle during use.

In other embodiments, the length adjustment and varus/valgus force application mechanisms may be different. For example, FIGS. 8 and 9 are a side elevational view and a top plan view of a knee-stretching device 100 according to another embodiment of the invention. The knee-stretching device 100 is substantially similar to the knee-stretching device 10 described above; therefore, those parts not described here may be assumed to have the same structure as those described above.

The knee-stretching device 100 includes a lever portion 102 and a fulcrum portion 104. The lever portion 102 has first and second ends 106, 108, and the fulcrum portion 104 is disposed between the first and second ends 106, 108. Like the lever portion 12, the lever portion 102 is adapted to be adjustable in length to allow for the application of traction forces; however, its mechanism of doing so is different than that of the lever portion 12.

Specifically, the lever portion 102 includes much the same arrangement as in the lever portion 12: a first part 110, an adapter part 112 mounted within the first part 110, and a moveable part 114 that is mounted for sliding movement on the adapter part 112. As in the lever portion 12, the moveable part 114 defines the second end 108 of the lever portion 102. However, unlike the lever portion 12, the moveable part 114 of the lever portion 102 includes a set of regularly spaced, linearly arranged holes 116 through its upper surface. A button 120 sized to fit snugly within the holes 116 is attached to the adapter part 112 and is spring-biased toward a position in which it protrudes through one of the holes 116, thus fixing the length of the lever portion 102. In order to adjust the length of the lever portion 102, the user would depress the button 120 until it does not protrude from a hole 116, slide the moveable part 114 to a new length that corresponds with the position of another one of the holes 116, and allow the button 120 to snap into place within the new hole 116. The lever portion 102 can thus assume any one of a defined set of lengths that corresponds with the position of the holes 116. More holes 116 can be added for a greater range of length adjustment, and the holes 116 can be spaced more closely together for finer increments of length adjustment.

The button 120 and hole 116 mechanism of the knee-stretching device 100 does not allow the moveable part 114 of the lever portion to pivot; therefore, another mechanism in the knee-stretching device 100 provides the out-of-plane pivot that allows the application of varus and valgus forces to the knee. Specifically, as shown in FIGS. 8 and 9, the fulcrum portion 104 forms a hollow socket 122 in its midsection. A round, tubular portion 124 is sized and adapted to rotate within the socket 122. One end of the tubular portion 124 is fixedly connected to the lever portion 102. With this arrangement, the entire lever portion 102 can pivot with respect to the fulcrum portion 104, as shown in FIG. 9. The rotational position of the lever portion can be fixed by tightening a hand screw 126 that extends into the socket 122 and contacts the tubular portion 124 to stop it from rotating. Therefore, the user or clinician can select a rotational position that provides for a particular varus or valgus force on the knee.

The Use of Knee Stretching Devices

As was described above, one use of the knee-stretching devices 10, 100 according to embodiments of the invention is to facilitate patient-controlled knee extension stretching exercises. The particular treatment and exercise methods will depend on a number of factors including the patient's age, diagnosis, amount of knee motion, patient motivation, and post-treatment pain, as well as the judgment of the responsible clinicians.

The knee-stretching devices 10, 100 can be used in or as adjunct to physical therapy after knee replacement or after surgical intervention with any other diagnosis in which a patient lacks knee extension, or for improvement of knee strength, function, and range of motion in cases not requiring surgery. However, the present inventor has found that there are also specific benefits to using the knee-stretching devices 10, 100 prior to surgery in some cases.

For example, several studies have shown that the preoperative knee range of motion in cases of total knee arthroplasty is the most important factor affecting the postoperative range of motion. While the present inventor does not wish to be bound by any particular theory, some patients who undergo a total knee arthroplasty may not have had full flexion/extension range of motion for a relatively long time before the surgical procedure. These patients may fall into a pattern of, for example, co-contracting the hamstrings and quadriceps or not moving the affected knee through its full range of motion because of pain. Other patients may lack the muscle strength to apply a force sufficient to put the knee into adequate extension. In these cases, use of the knee-stretching devices 10, 100 prior to surgery may help to increase the knee range of motion postoperatively.

The longer a patient has lacked knee extension, the longer it may take for the patient's range of motion to improve. For example, if the patient has a stiff arthritic knee that is to be replaced, it may take three to four months to achieve the desired range of motion.

When using the knee-stretching devices 10, 100, the length of the lever portion 12, 102 should be adjusted so that the angle of the harness 38 is equal to or slightly greater than the amount of knee extension that the patient lacks. For example, if the patient lacks 15 degrees of knee extension, the harness 38 should be pulling the leg distally at approximately a 15 degree angle. The amount of traction may be varied so as to make the stretch as comfortable as possible without making the harness angle so great that the harness 38 slides off the foot. If either the medial or lateral compartment of the knee is to be unloaded, the device can be positioned as described above so as to apply the appropriate varus or valgus force. As knee extension improves over the course of treatment, adjustments in the length of the device may be made to reduce the level of traction force that is applied to the leg.

During use, the patient may be advised to relax and breathe deeply while stretching. The patient may also be advised not to stretch to the point of “tensing up” or to the point where he or she experiences a significant increase in pain. Additionally, the patient may be asked to contract his or her quadriceps muscles during stretching, if those muscles can be successfully isolated. The stretch may be held for 30 to 60 seconds or longer, and may be repeated, for example, three to ten times. The patient may be asked to stretch three to five times per day. Alternatively, the knee-stretching devices 10, 100 can be used like “knee boards,” so that the knee is held in the extended position for a protracted period of time, for example, with a recommendation of stretching for a total of ten minutes per session, approximately four times per day.

Regardless of the precise number of repetitions or method of use, the patient should be able to relax. Patients may be advised to perform their usual exercise routine first, or to ride an exercise bike before using the knee-stretching devices 10, 100, so that the knee is relaxed and warmed up before the knee-stretching devices 10, 100 are used. After using the knee-stretching device 10, 100, the affected area may be iced for pain and inflammation control. An exercise log in which the patient records how much time the knee-stretching device 10, 100 was used may be helpful in ensuring correct use and optimal outcome.

If the thigh rest 34 of the knee-stretching device 10, 100 is too small or too large to fit a patient's thigh properly, it can be bent manually to some extent to obtain a better fit. Additionally, thigh rests 34 may be made to whatever sizes are desired to accommodate different patients. Although knee-stretching devices 10, 100 may be made of a variety of materials, it may be advantageous to make them free of latex and other materials that can cause allergic reactions.

The knee-stretching devices 10, 100 may be used in a variety of other ways and with a variety of other diagnoses at the discretion of the responsible clinicians. However, as those of skill in the art will understand, use of the knee-stretching devices 10, 100 may be contraindicated in some circumstances. For example, use of the knee-stretching devices may be contraindicated in cases of severe osteoporosis; malignancy in the lower extremity; severe, abnormal joint alignment; bony block inhibiting knee extension; after a recent fracture, if not cleared by a physician; whenever there is sharp, acute pain with joint movement; whenever there is evidence of an acute inflammatory or infectious process in or around the knee joint; whenever there are open wounds located where the strap or kneepad contact; and in patients with thrombophlebitis. The knee-stretching devices 10, 100 should also be used with caution in patients with healing wounds located where the strap or kneepad contact the skin and in patients with fragile skin.

The invention has thus been described with respect to certain embodiments. However, the described embodiments are intended to be exemplary, rather than limiting. Modifications and changes may be made within the scope of the invention. 

1. A knee-stretching device, comprising: an elongate lever portion having a first end and a second end; a fulcrum portion pivotally connected to the lever portion intermediate the first and second ends, the fulcrum portion having an upper end connected to the lever portion through a lever pivot, and a lower end adapted to rest on a leg; a harness connected to the lever portion proximate to the second end; and an out-of-plane pivot connecting portions of the knee-stretching device, the out-of-plane pivot allowing at least a part of the lever portion to transmit force in a plane other than a knee flexion-extension plane of motion, such that the knee-stretching device is adapted to transmit forces to the distal portion of the leg in the knee flexion-extension plane of motion and in other planes of motion.
 2. The knee-stretching device of claim 1, wherein the first end of the lever portion is adapted to receive the application of manual force and thereby to move in a first direction, thus causing the second end of the lever portion to move in a second, opposite direction.
 3. The knee-stretching device of claim 2, wherein the harness is adapted to hold and apply force to a distal portion of the leg while the lower end of the fulcrum portion rests on a more proximal portion of the leg.
 4. The knee-stretching device of claim 3, further comprising an eyebolt connecting the harness and the lever portion.
 5. The knee-stretching device of claim 4, wherein the second end of the lever portion is upwardly angled.
 6. The knee-stretching device of claim 5, wherein the first end of the lever portion is upwardly angled.
 7. The knee-stretching device of claim 6, wherein the eyebolt is connected to an upper surface of the lever portion proximate to the second end.
 8. The knee-stretching device of claim 1, the lever portion further comprising: an elongate, tubular first part that includes the first end of the lever portion; an adapter part mounted within the first part; and an elongate, tubular moveable part that includes the second end of the lever portion mounted for sliding movement along the adapter part; wherein movement of the moveable part along the adapter part alters the overall operational length of the lever portion.
 9. The knee-stretching device of claim 8, further comprising a clamp mechanism mounted on the moveable part, the clamp mechanism being adapted to fix the length of the lever portion.
 10. The knee-stretching device of claim 9, wherein the clamp mechanism comprises a ring with an adjustable diameter.
 11. The knee-stretching device of claim 1, wherein the out-of-plane pivot comprises a pivot between the upper and lower ends of the fulcrum portion.
 12. The knee-stretching device of claim 1, wherein the lever portion is adjustable in overall length.
 13. A method of increasing knee strength, function or range of motion in a patient, comprising: causing the patient to simultaneously apply a knee extension force and one or more forces selected from the group consisting of a traction force on the knee, a varus force on the knee, and a valgus force on the knee using a first class lever device positioned to accept force from the arms of the patient and transmit that force to the patient's knee through a distal portion of the patient's leg.
 14. The method of claim 13, wherein the patient is in need of a total knee arthroplasty and the method is performed prior to surgery.
 15. The method of claim 13, wherein the patient is in need of surgery and the method is performed prior to surgery.
 16. A knee-stretching device, comprising: lever means for accepting a manual force and transmitting that force to a knee through a distal portion of a lower extremity; harness means coupled to the lever means for holding the distal portion of the lower extremity; fulcrum means pivotally connected to the lever means for allowing the lever means to pivot in a first plane of motion while the fulcrum means remains fixed in position; and out-of-plane pivot means for allowing the lever means to transmit force in the first plane of motion and in planes of motion other than the first plane of motion. 